As electronic devices having a lid that opens, closes or repositions about a hinge or hinges (e.g., a clamshell laptop computer) become lighter, it becomes more difficult to open the lid of the device, e.g., using one finger. That is because the bottom half of the devices, which were once quite heavy, are now light enough that when a user tries to open the lid with one finger, they end up lifting not only the upper part (e.g., screen half of a laptop) but also the bottom part (e.g., keyboard containing part of the laptop).
This difficulty is in part due to the friction in device hinges remaining constant, even as devices become lighter. Most thin computers now require at least one finger to hold the bottom half of the computer down and another finger, usually on the user's opposite hand, to lift the lid.
In order to make it easier to lift the lid with one finger, leaving the other hand free, some computers have hinges with relatively low friction. This does make it possible to lift the lid with one finger, but it also means that when the laptop is open, the upper part (e.g., screen) is not very stable and not suitable for use (particularly if the screen is a touch screen) or while carrying the computer. It has been proposed that a computer could have a hinge whose friction can be varied electronically. When power is applied to the hinge, the friction either increases or decreases.